KYIV —
The Organization for Security and Cooperation in Europe says the situation in eastern Ukraine remains volatile, with eight of its observers being held by armed groups.

The OSCE is also sending a high-level Swiss diplomat to Ukraine for peace talks, but the diplomatic effort comes amid worrying reports of increased activity by Russian-backed separatist militias in the country’s east.

OSCE spokesman Michael Bociurkiw on Friday gave few details on the condition of the eight kidnapped monitors, but said the organization is confident that they are “in fairly good condition.” He said no group has owned up to their abduction more than two weeks ago.

“The special monitoring mission to Ukraine has unfortunately not yet re-established communication with the four monitors from the Donetsk team, and the four monitors from the Luhansk team, with whom we lost contact on the 26th and 29th of May, respectively," said Bociurkiw.

"I want to make it clear that no one individual or group has come forward to claim responsibility. We do, however, appeal to anyone or any groups that are holding our colleagues to make immediate contact," he said.

Of the eight abducted monitors, the OSCE has identified the nationalities of four: they are from Switzerland, Estonia, Turkey and Denmark. The nationalities of the other four have not been made public.

Their continued detention comes amid accusations by Ukrainian officials that separatists in the fractious east drove tanks across the border from Russia. Ukraine accuses Russia of fueling the conflict in Ukraine's Russian-speaking east after Ukrainians ousted their Russian-backed president in February.

Bociurkiw says the OSCE has also sent in a high-level Swiss diplomat to engage in peace talks. He said the group now has 240 international monitors in Ukraine, and is planning to send more. He urged the kidnappers to not interfere with their work.

“We want to make one thing clear. It’s that it’s in nobody’s interest for anybody or any entity to hold our monitors. In fact, their — whatever you want to call it, detention or whatever — hampers our ability to do the work we’re we’re supposed to be doing. We’re here for the people of Ukraine. We’re here to bring about de-escalation. So it’s very important that our teams are able to operate in an unfettered fashion, that they have access to all areas of Ukraine. And also don’t forget that we’re not only talking [about] eight unarmed civilians individuals here. We’re talking about families, we’re talking about parents, we’re talking about kids as well; their kids have been separated from them for a very long time," he said.

Although officials from both Ukraine an Russia have indicated they will talk about peace, any such talks are likely to be complicated by Russia’s threat to cut off Ukraine’s natural gas supply after price negotiations broke down earlier in the week.